1. Field of the Invention
The present invention relates generally to a magnetic transfer apparatus for writing a servo signal to a magnetic recording medium by a magnetic transfer technology, and an optical inspection apparatus for inspecting a condition of a surface of the magnetic recording medium, which are particularly featured in greasing agent used in these apparatus. More particularly, the invention relates to a magnetic transfer apparatus, which is featured by a greasing agent used in the apparatus, for writing a positioning servo signal for a data writing/reading head written on a surface of a magnetic recording medium to a magnetic recording medium by a magnetic transfer technology in a hard disk drive employing a magnetic film as a storage material as a currently major trend as external storage device of computers, and an optical inspection apparatus, which is featured by a greasing agent used in the apparatus, for inspecting scratch on the surface of a magnetic recording medium and contaminating condition of before and after magnetic transfer. Also, the present invention relates to a magnetic recording medium to be produced by the magnetic transfer apparatus.
2. Description of the Related Art
In a hard disk drive used as an external storage device of a personal computer, a magnetic head is floated above a surface of a rotating magnetic recording medium by means of a floating mechanism called as slider with maintaining a distance of several tens nanometer for writing and reading data. For example, on the magnetic recording medium, data tracks are arranged concentrically. A magnetic head of a magnetic disk for writing and reading data is moved to a target side on the data track at high speed and is positioned to write bit information on the data track or to read out the already written bit information for writing and reading data.
On the other hand, on the magnetic recording medium, a positioning signal (servo signal) for detecting a relative position between the magnetic head and the data track is written in concentric fashion. The magnetic head performing writing and reading data detects own position at a given interval. For avoiding offset of the center of the servo signal from the center of the magnetic recording medium (or the center of a trace of the magnetic head), the servo signal is written on the medium using a dedicated apparatus called as servo writer after assembling the medium in the hard disk drive. Writing by the servo writer is performed by writing the servo signal to the magnetic recording medium using a servo signal writing head, for example.
On the other hand, the hard disk drive on development reaches a recording density of 20 Gbits/in2. The recording density is increasing at a speed of 60% or more per year. Associating with this, the density of the servo signal for enabling the magnetic head to detect own position is increased to inherently increase writing period by means of the servo writer. Increasing of the writing period by the servo writer should lower productivity of the hard disk drive to cause increasing of the cost.
In order to avoid increasing of the writing period of the servo signal, it has been recently proposed a transfer system for writing the servo signal in a lump by a magnetic transfer apparatus. Development of technology has been performed (for example, Japanese Patent Application Laid-Open No. 10-40544, Japanese Patent Application Laid-Open No. 11-25455). Writing of the servo signal by magnetic transfer, problem may be caused in transfer when scratch or contamination is present on the surf ace of the magnetic recording medium. Therefore, the magnetic recording medium has to be inspected by an optical type inspection apparatus.
In the magnetic transfer apparatus and the optical inspection apparatus, for transporting the magnetic recording medium or performing magnetic transfer and inspection for the magnetic recording medium, various movable portions are present. To the movable portion, a lubricant such as grease is applied. The grease can generate a gas due to friction upon operation of the movable portion or rising of temperature of the overall apparatus. Such gas may deposit on the surface of the magnetic recording medium to adversely affect for magnetic transfer or inspection.